plant anatomy also known as micromprphology of plants and plant- or vegetable-histology, is...
Post on 22-Dec-2015
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Plant AnatomyAlso known as Micromprphology
of plants and plant- or vegetable-histology, is
concerned with the microscopic structure of the tissues, cells and organs of
plants.
Plant tissuesA tissue is a group of coherent cells
having similar form and function and have common origin.
Tissues are classified according to stage of development to:
Meristematic tissue: the cells have the ability of division.
Mature (permanent): the cells lost the power of division .
Meristematic tissueThey characterized by:
1 -Thin walled. 2- Isodiametric.3 -With dense cytoplasm.4 -With large nucleus.5 -Have proplastides.6 -No intercellular spaces.7 -No vacuole or presence of minute
ones.8 -No reserve food materials.
Classification of meristems
Apical meristems: located at the growing points of stems and roots e.g. those
present in stem and root apices.Intercalary meristems: present between two
permanent zone, present at base of internodes e.g. sugarcane and maize.
Lateral meristems: present laterally and cause increase in diameter of plant.
Different types of mature tissues
1 -Parenchyma2- Collenchyma3 -Sclerenchyma4- Epidermis5 -Endodermis6- Pericycle7 -Cork (phellem)8- Laticiferous
tissue9 -Sieve tissue10- Tracheary
tissue11 -Vascular tissue12- Secretory
structures13-Nectaries
1 -ParenchymaCharacters:
1 -Simple living cells.2 -Have primary
cellulosic thin wall with simple pits.
3 -Have intercellular spaces.
4 -They may be elongated,
isodiametric or lobed.
Occurrence:
1 -In cortex and pith of stems and roots.
2 -Associated with xylem and phloem.
3 -In leaves and fruits.
Function:
1 -In aeration.
2 -In photosynthesis.
3 -Storage of water, protein, minerals, etc..
4 -May become meristematic and divide .
2 -Collenchyma
Characters:
1 -Simple living tissue.
2 -Have primary cellulosic thick wall with simple pits.
3 -May have intercellular spaces.
4 -They are elongated cells.
Types:Lamellar: thickening on
tangential walls.Angular: thickening on
angles between the cells.
Lacunar: thickening on walls facing the
intercellular spaces.
Occurrence:1 -Under epidermis of stems.2 -Cortical tissue and pericycle of
leaves.
Function: They are plastic tissue used for
mechanical support of soft plants.
3 -Sclerenchyma
They are dead cells when mature with thick secondary walls, they
are elastic tissue used for mechanical support. Sclerenchyma
has two types; fibres and sclereids.
A- Fibres
They are dead cells have pitted walled with narrow Lumina and
pointed apices, xylary fibres are lignified while extraxylary fibres may be lignified or non-lignified.